There is an FT (Fault-Tolerant) information processing systems having a plurality of CPUs (Central Processing Units) and, when a synchronization deviation occurs among the CPUs, a CPU having a fault is separated from the system.
For example, Unexamined Japanese Patent Application Kokai Publication No. 2006-172390 discloses an FT system constructed by duplicated computer systems. The duplicated computer systems record repairable fault information and unrepairable fault information while operating. When a synchronization deviation occurs between CPUs, the duplicated computer systems are set to an active mode and a standby mode by using the recorded fault information.